1. Field of the Invention
This invention relates to seal systems which are adapted to allow the introduction of surgical instrumentation into a patient's body. In particular, the invention is applicable to a cannula assembly wherein a cannula housing includes or is adapted to receive a seal assembly to sealingly accommodate instruments of different diameters inserted through the seal assembly and cannula.
2. Description of the Related Art
In laparoscopic procedures surgery is performed in the interior of the abdomen through a small incision; in endoscopic procedures surgery is performed in any hollow viscus of the body through narrow tubes or cannula inserted through a small entrance incision in the skin. Laparoscopic and endoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e. provisions must be made to ensure that gases do not enter or exit the body through the incision as, for example, in surgical procedures in which the surgical region is insufflated. Moreover, laparoscopic and endoscopic procedures often require the surgeon to act on organs, tissues, and vessels far removed from the incision, thereby requiring that any instruments used in such procedures be relatively long and narrow.
For such procedures, the introduction of a tube into certain anatomical cavities such as the abdominal cavity is usually accomplished by use of a trocar assembly comprised of a cannula assembly and an obturator assembly. Since the cannula assembly provides a direct passage for surgical instrumentation from outside the patient's body to access internal organs and tissue, it is important that the cannula assembly maintain a relatively gas-tight interface between the abdominal cavity and the outside atmosphere. The cannula assembly thus generally includes a cannula attached to a cannula housing: containing a seal assembly adapted to maintain a seal across the opening of the cannula housing.
Since surgical procedures in the abdominal cavity of the body require insufflating gases to raise the cavity wall away from vital organs, the procedure is usually initiated by use of a Verres needle through which a gas such as CO2 is introduced into the body cavity, thereby creating a pneumoperitoneum. Thereafter, the pointed obturator of the obturator assembly is inserted into the cannula assembly and used to puncture the abdominal wall. The gas provides a positive pressure which raises the inner body wall away from internal organs, thereby providing the surgeon with a region within which to operate and avoiding unnecessary contact with the organs by the instruments inserted through the cannula assembly. Following removal of the obturator assembly from the cannula assembly, laparoscopic or endoscopic surgical instruments may be inserted through the cannula assembly to perform surgery within the abdominal cavity.
Without the obturator assembly to block the flow of insufflation gas out from the cavity, other structure must be provided to maintain a relatively fluid-tight interface between the abdominal cavity and the outside atmosphere. Generally in the context of insufflatory surgical procedures, there are two sealing requirements for cannula assemblies. The first requirement is to provide a substantially fluid-tight seal when an instrument is not being introduced into or is not already present in the cannula. The second requirement is to provide a substantially fluid-tight seal when an instrument is being introduced into or is already present in the cannula. Additionally, as endoscopic and laparoscopic surgical procedures and techniques have advanced, it has become desirable to accommodate surgical instrumentation of varying outside diameters through a single cannula assembly in a given surgical procedure, thereby minimizing the number of cannulae required and facilitating efficiency in the surgical procedure.
To meet the first sealing requirement, various seals have been provided for maintaining the pneumoperitoneum in the cavity when no trocar or other surgical instrument is present in the cannula. For example, a pivotally mounted flapper valve may be provided which pivots open upon insertion of an instrument and pivots closed, under a spring bias, once the instrument is removed. Conventional flapper valves may also be manually opened by pivoting a lever provided on the exterior of the housing. An example of such a flapper valve is disclosed in U.S. Pat. No. 4,943,280 to Lander. Trumpet valves are also well known for use in sealing a cannula assembly in the absence of a surgical instrument
U.S. Pat. No. 4,655,752 to Honkanen et al. discloses a cannula including a housing and first and second seal members. The first seal member is conically tapered towards the bottom of the housing and has a circular opening in its center, while the second seal member is cup-shaped. The second seal member includes at least one slit to allow for passage of instruments.
U.S. Pat. No. 4,929,235 to Merry et al. discloses a self-sealing catheter introducer having a sealing mechanism to prevent blood or fluid leakage that includes a planar sealing element having a slit, and a conical sealing element proximal of the planar sealing element so that if the distal planar sealing element is moved proximally it rests upon the conical sealing element, each sealing element being adapted to surround a tube.
U.S. Pat. Nos. 4,874,377 and 5,064,416 to Newgard et al. relate to a self-occluding intravascular cannula assembly in which an elastomeric valving member is positioned transversely to a housing and is peripherally compressed to cause displacement, distortion and/or rheological flow of the elastomeric material. A frustoconical dilator projection is provided which cooperates with the elastomeric valving member in moving the valving member to a non-occluding position.
U.S. Pat. No. 5,104,3838 to Shichman relates to a trocar adapter seal which is adapted to be associated with a cannula assembly and which advantageously reduces the diameter of the cannula assembly to accommodate instruments of smaller diameter. The trocar adapter seal may be removed from the cannula assembly so that the cannula assembly may once again accommodate instruments of larger diameter. WO 93/04717 to Mudler et al. describes a similar trocar adapter seal system in which a pair of seal adapter plates are slidably mounted to the cannula housing and may be selectively positioned transverse the cannula housing aperture for accommodating surgical instrumentation therethrough.
Cannula assemblies have also been developed which are provided with a series of resilient sealing elements having a central aperture, e.g., commonly assigned, co-pending applications Ser. No. 07/874,291 filed Apr. 24, 1992 and Ser. No. 07/873,416 filed Apr. 24, 1992 both abandoned. Upon insertion of an instrument, the sealing elements resiliently receive the instrument, while maintaining a seal around the instrument across a range of instrument diameters, e.g., 5 to 12 mm. Upon withdrawal of the instrument, a fluid-tight seal is provided by the internal sealing elements.
Although attempts have been made to provide a seal assembly as part of or for use in conjunction with a cannula assembly which maintains the integrity of the seal between the body cavity and the atmosphere outside the patient's body, seal systems provided to date have failed to address the full range of surgeons' needs, especially when it is desired to utilize different instruments having different diameters therethrough.